Optimization of Drying Process of Rambutan by Combined Method of Osmosis Ultrasound and Complementary Drying of Hot Air
Muhammad Farooq1*, Elham Azadfar2, Zohre Bahrami3, Mahniya Sharifi3, A. Shakoor4, Shabir Ahmed5, Iftikhar Ahmed Solangi1, Muhammad Noman Khan6, Memona Siddique7, Naila Ilyas8*, Muhammad Bakhtiar9, Mohamed El-Fatieh Ismael1 and Wang Yunyang1
Drying is widely known to be one of the common processes in the food industry to increase the shelf life of fruits and vegetables. Using osmosis-ultrasound before drying with hot air causes the preservation of nutrients in products and reduces heat energy to remove the produc water. In this study, after osmosis pretreatment, samples were put under an osmosis dehydration process. First, using Osmosis-ultrasound with 40.5% concentration in Sekanjabin solution then dried in an oven at a temperature of 70°C. The characteristics of solid gain, water and weight loss, shrinkage and rehydration were evaluated. The obtained results showed that by increasing the concentration of weight and water loss, solid gain increased. Accordingly, in a higher concentrated osmotic solution, the osmotic pressure, which is a key factor in mass transfer in the osmotic dehydration process, increases by increasing concentration, the percentage of solids gain increased; shrinkage and rehydration decreased. Conclusively, the drying of Rambutan by use of osmosis-ultrasound dehydration process when compared to osmotic dehydration, showed a significant decrease in the shrinkage of fruits resulting in rehydration, i.e., causing the percentage of solid gain, weight and water loss to be increased.